Fix Bugzilla 24582 - Detect unsafe cast(bool[])

Allow literal cast

Make deprecation

Add specific supplemental message

compiler/src/dmd/safe.d

@@ -219,6 +219,14 @@ bool isSafeCast(Expression e, Type tfrom, Type tto, string* msg = null)
             return false;
         }
 
+        // For bool, only 0 and 1 are safe values
+        // Runtime array cast reinterprets data
+        if (ttobn.ty == Tbool && tfromn.ty != Tbool && e.op != EXP.arrayLiteral)
+        {
+            if (msg)
+                *msg = "Array data may have bytes which are not 0 or 1";
+        }
+
         // If the struct is opaque we don't know about the struct members then the cast becomes unsafe
         if (ttobn.ty == Tstruct && !(cast(TypeStruct)ttobn).sym.members ||
             tfromn.ty == Tstruct && !(cast(TypeStruct)tfromn).sym.members)

compiler/test/fail_compilation/bool_cast.d

@@ -0,0 +1,15 @@
+/*
+REQUIRED_ARGS: -de
+TEST_OUTPUT:
+---
+fail_compilation/bool_cast.d(13): Deprecation: cast from `ubyte[]` to `bool[]` not allowed in safe code
+fail_compilation/bool_cast.d(13):        Array data may have bytes which are not 0 or 1
+---
+*/
+
+void main() @safe
+{
+    ubyte[] a = [2, 4];
+    auto b = cast(bool[]) a; // reinterprets a's data
+    auto c = cast(bool[]) [2, 4]; // literal cast applies to each element
+}